Machine-gun fire reverberated around the Syrian town of Rastan near the central city of Homs on Tuesday as military operations continued for a third straight day, a human rights activist said.
"Machine-gun fire was heard in Rastan. Search and cordon operations are continuing in the town," the activist said on condition of anonymity, adding that explosions too were heard.
He said that residents of the town had attacked a police station and seized weapons near the place where a girl, identified as Hajar al-Khatib, and 10 other civilians were killed on Sunday.
In Homs, protesters on Monday night set fire to a vehicle belonging to the security services, expressing outrage at the crackdown in nearby Talbisa and Rastan, the activist added.
Since dawn on Sunday, dozens of tanks have surrounded the two towns and the village of Teir Maaleh to quell the protests around Homs, Syria's third largest city, 160 kilometres (100 miles) north of Damascus.
South of the capital, he said that during Monday night "security forces conducted search operations in Hiraki", near the city of Daraa, another focal point for the protests against President Bashar al-Assad's rule.
More than 1,100 civilians have been killed and at least 10,000 arrested since the protests against Assad's autocratic government erupted in mid-March, according to human rights organisations.
Foreign journalists are barred from travelling around Syria, making it difficult to report on the unrest and verify witness accounts.
The government insists the unrest is the work of "armed terrorist gangs" backed by Islamists and foreign agitators.
It initially responded to the revolt by offering some concessions, including lifting the state of emergency in place for nearly five decades, but coupled this with a fierce crackdown.
The opposition has dismissed calls for dialogue, saying that can take place once only the violence ends, political prisoners are freed and reforms adopted.